Method of operating a fuel cell apparatus and fuel cell apparatus having a charge limiter

Abstract

A method for operating a fuel cell device, the fuel cell device having a fuel cell, and a motor vehicle having a drive system and the fuel cell device are disclosed. In order to avoid energy which has been made available by the fuel cell device being used merely to heat the fuel cell and therefore not being available for a consumer, there is provision according to the invention that the energy to be stored is limited as a function of the ambient temperature and the fuel cell device has for this purpose an ambient temperature-determining unit and a charge limiter which is connected to the ambient temperature-determining unit in a control signal-transmitting fashion.

The invention claimed is: 
     
       1. A method for operating a fuel cell device, the method comprising:
 making electrical energy available from a fuel cell, and 
 at least partially storing the electrical energy in a suitable energy storage device, 
 wherein a maximum amount of electrical energy to be stored is predefined as a function of an ambient temperature of the fuel cell. 
 
     
     
       2. The method of  claim 1 , further comprising comparing the ambient temperature with a predefined temperature and limiting the maximum amount of electrical energy to be stored if the ambient temperature is below the predefined temperature. 
     
     
       3. The method of  claim 1 , further comprising determining an ambient temperature which is expected to prevail during an imminent starting process as the ambient temperature. 
     
     
       4. The method of  claim 1 , further comprising predefining the maximum amount of electrical energy to be stored in a limited way such that a difference in electrical energy between a maximum amount of electrical energy which can be stored and the predefined maximum amount of electrical energy to be stored is sufficient for the fuel cell to heat itself up sufficiently by means of internal losses when the difference in electrical energy is made available at a start of the fuel cell device operation. 
     
     
       5. The method of  claim 1 , wherein storing the electrical energy is done at least partially in an accumulator of the fuel cell. 
     
     
       6. A fuel cell device comprising
 a fuel cell, 
 an accumulator for storing electrical energy, which is connected to the fuel cell in an electrical energy-transmitting fashion, 
 an ambient temperature-determining unit, and 
 a charge limiter which is adapted to limit a maximum amount of electrical energy to be stored in the accumulator as a function of a control signal of the ambient temperature-determining unit. 
 
     
     
       7. The fuel cell device of  claim 6 , wherein the ambient temperature-determining unit comprises a temperature prediction unit for predicting expected ambient temperatures. 
     
     
       8. The fuel cell device of  claim 6 , wherein the ambient temperature-determining unit comprises a data input for receiving temperature data representing expected ambient temperatures. 
     
     
       9. The fuel cell device of  claim 6 , wherein the accumulator is a rechargeable battery which stores drive electrical energy for a motor vehicle. 
     
     
       10. A motor vehicle comprising a drive system and the fuel cell device of  claim 6 , wherein the fuel cell device is connected to the drive system in an electrical drive energy-transmitting fashion.